1. Field of the Invention
The present invention concerns a process for the production of carbon-containing electrodes for electricity (current) producing and/or electricity-storing cells as well as their application.
2. Description of the Related Art
In the past, efforts have been made to produce organic polymers which can be utilized as so called "intrinsically conducting polymers", used in the field of electro-chemistry as electrode materials.
These efforts are of particular importance also because the previously used metallic or metal containing electrodes, in particular the poisonous heavy metal-electrodes, either in the form of their utilization as primary or secondary cells or during their disposal or recycling, create huge environmental problems. This is because the contents of these heavy metal electrodes, in particular the very poisonous metals cadmium, nickel, copper lead and mercury, unavoidably reach the ground-water and the air as poisonous materials.
A further disadvantage of heavy metal-electrodes rests in the high specific weights of their metallic contents which poses almost insurmountable problems for use of the heavy metal electrodes in traction cells and also to obtain a cost efficient storage of photo-voltaically gained solar energy.
Intrinsically conducting polymers mentioned above are desirable because they are light and environmentally acceptable.
In their structure, conducting polymers obey structure-chemically all the same principles, in that they are polymers with conjugated double-bond-systems. Thus they are for example the polyacetylene, polyphenylene, polypryrrole, polyaniline, etc. polymers.
In pure condition, however, these compounds are not yet conductors; they have to be doped to turn them into conductors, meaning that one has to bring charged ions to the (CH).sub.x -chain, whereby in particular iodine, FeCl.sub.3, As.sub.5 and others play a role. By means of this doping the charges are withdrawn from the chain or charges are brought upon the chain so that an ionic conductance is created, which carries out the transport of current.
Another direction of the development is shown by the so called composite-electrodes which are produced by compounding (mixing) of a non-conducting organic thermoplast with a conducting carbon material like carbon black and/or graphite and/or carbon fibers. Here the organic thermoplast serves as a matrix for a conductor and the composite electrode takes on electrically conducting properties above a certain percentage of conductor carbon black and/or graphite, that is above the so called percolation point.
If one combines such a composite electrode additionally with the metals and/or metal oxides which have a chemical redox-potential, then primary and secondary cells or cells with combined properties can be built. In this connection reference is made to the DE-OS 36 18 881.